1. Field of the Invention
The present invention relates to a part mounting device for mounting electronic parts on a multi-sectional motherboard, a part mounting method, and a storage medium storing a program thereof.
2. Description of the Related Art
Conventionally, there was a part mounting device for mounting electronic parts (simply referred to as parts hereinafter) on a print circuit board (simply referred to as a board hereinafter) to be conveyed into the device by using a working head which can freely move upward and downward and is attached to a working tower which can freely move back and forth and to the left and right in a working space above the board. In recent years, the working tower has been normally attached with two or more working heads (currently, up to 8 is general) for improving an operation efficiency. The above described board includes various types such as a large-sized board on which approximately 100 parts are mounted, or a small-sized board on which parts whose number is a relatively small number such as several tens or ten-odd are mounted, etc.
If small-sized boards are conveyed one by one and parts are mounted thereon, a tact (ratio of the number of parts to be mounted on one board per hour) is degraded. This is because a considerable amount of time is required for conveying the boards and determining the positions of the boards. Therefore, a motherboard (multi-sectional board) is structured by connecting a plurality of such small-sized boards (childboards), for example, four or six boards; this motherboard is conveyed and mounted with parts; and the motherboard, for which this mounting process is completed and which is taken out, is cut into respective childboards in these days.
Similar to the case where parts are mounted on a normal single board, a working head sequentially completes a process for mounting parts on a first childboard, next on a second childboard, then on a third childboard, etc. according to a part mounting pattern corresponding to each of the childboards also in the case where parts are mounted on the above described motherboard. In this case, the working head performs the part mounting process by replacing a currently attached picking-up nozzle (simply referred to as a nozzle hereinafter) with a nozzle suitable for the type of a part to be mounted.
However, the above described nozzle replacement process must be performed with such a procedure that the working head returns the nozzle attached so far to a predetermined position (the position in which the nozzle is held before being attached) of a nozzle replacing device, then moves to the position in which the nozzle suitable for the part to be picked up is held, and attaches the desired nozzle. Therefore, the amount of time required for this procedure is much more than that required for the process for picking up parts and mounted them on a board. As a result, it prevents the tact from being improved. However, since the nozzle replacement process is essential, almost no consideration has been given to the way of improving the tact, which relates thereto, up to now.